Efficiency of ATM Networks in Transporting Wide-Area Data Traffic

For performance and economic reasons, ATM networks must efficiently support the Internet family of protocols. We compare the transmission efficiency achieved by a range of ATM-related protocols when transporting TCP and UDP wide-area traffic. We also calculate the efficiency effects of several non-standard compression techniques, and discuss how to implement these techniques cheaply. To assure an accurate workload characterization, we drive these calculations with millions of wide-area packet lengths measured on the current Internet. We find that networks using standard ATM procedures are inefficient in carrying wide-area data traffic − depending on the protocols used, efficiency as seen by an application program ranges between 40 and 53%. Moreover, due to interaction between TCP-IP datagram lengths and ATM cell padding, efficiency responds abruptly to changes in certain protocol parameters − for example, a 4byte increase in ATM cell payload size can yield a 10% increase in efficiency. Using one compression technique in isolation can improve efficiency by 12%, and simultaneously using three techniques can improve it by 34%. These issues should be considered when designing future ATM networks.